Judging from the frequency with which hemagglutinin-inhibiting antibodies for reoviruses have been demonstrated in sera of patients at this hospital( l ) , infections with these viruses must be very common; yet there are few reports of isolation of reoviruses in animals( 2-4) and even fewer from humans( 5-8). The data presented here indicate that the cytopathic effects (CPE) of all 3 types of reoviruses may be markedly increased in rolled rhesus kidney tissue cultures (MKTC) as compared with stationary cultures of the same kind, thus permitting more rapid and efficient isolation and identification of these viruses.Materials and methods. The same inoculum of reovirus types 1, 2 and 3(9) was introduced into 60 tubes of MKTCO for each type; one-half of them were incubated in stationary racks and the rest on a roller drum making 15 revolutions per hour (rph). All the cultures were kept in the same incubator a t 37°C. The reoviruses used were: types 1 (Lang) and 3 (Abney), obtained from Dr. Leon Rosen, and type 2 (strain 988) isolated in this laboratory(1). Cultures were ob-served for CPE and fluids from 5 tubes of each set were harvested daily, pooled, and kept frozen at -2OOC until they were titrated simultaneously for infectivity and hemagglutinins. Human adult "0, Rh-negative" erythrocytes were used for hemagglutination (HA). The technics are described elsewhere (10). In other experiments, stocks of these 3 viruses and another type 2 strain (I),), also obtained from Dr. Rosen, were incubated at 37OC; infectivity and hemagglutinins were assayed a t intervals over a period of 42 days. Reoviruses type 1 and 2 (988) were also assayed before and after incubation at 56°C for 45 minutes. Infectivity was assayed in roller tube cultures, 5 tubes per dilution, in which CPE was roughly quantitated over a period of 7 days. Blind passages were not done. The maintenance medium contained 0.2% bovine plasma albumin, 0.2% yeast extract, and 2% chicken serum in Earle's balanced salt solution plus antibiotics (250 units of penicillin, 250 pg of streptomycin and 100 units of nystatin per ml).Results and discussion. CPE (Table I) TABLE I. CPE" and Lysis of Rolled (R) and Stationary (S) MKTC by Reoviruues. Days at Type 1 Type 2 Type 3 37°C R S R S RS 1 0 0 0 0 0 0 2 0 0 0 0 ++ 0 0 0 0 ++++, p + 3 ++ 4 + + + + , p 0 0 5 ++++, c 0 ++,+++ 0 ++++, p 0 ++, +++ ++++,c 0 0 + + + + , c ++ * Cytopathic effect: +, <25%; ++, 26-50%; +++, 51-7596; ++++, >75% tissue eells damaged. P, partial lysis; C, complete lysis of cells.
